Combustor for a steam generator



D 1965 R. T. BRADY ETAL COMBUSTOR FOR A STEAM GENERATOR 2 Sheets-Sheet 1Original Filed May 6, 1963 INVENTORS ROBERT T. BRADY MICHAEL J M -INERNEY JOSEPH L, CZIE BY flu ATTO RNEY Dec- 1965 R. 'r. BRADY ETAL COMBUSTORFOR A STEAM GENERATOR 2 Sheets-Sheet 2 Original Filed May 6, 1963 FIGBINVENTORS ROBERT T. BRADY MICHAEL J. MQINERNEY JOSEPH L cal: BY

ATTORNEY United States Patent 3,226,038 CQMBUSTOR FOR A STEAM GENERATORRobert T. Brady, Elrnhurst, Michael J. Mclnerney, Highland Park, andJoseph L. Czyl, Harvey, lll., assignors to Vapor Corporation, Chicago,111., a corporation of Delaware Continuation of application Ser. No.278,329, May 6, 1963. This application Apr. 20, 1965, Ser. No. 456,597 4Claims. (Cl. 239-405) This is a continuation of application Serial No.278,329, filed May 6, 1963, now abandoned.

This invention relates in general to a combustor or burner for a boileror steam generator, and more particularly to a combustion system capableof keeping combustion within a chamber and aiding in balancingdistribution of the resultant energy, and still more particularly to aburner assembly for providing an eflicient combustion system.

The combustor of the present invention generally includes a fire potarranged within a casing that defines therewith a plenum chamber. Air issupplied through the plenum chamber to a burner assembly which ismounted in association with a combustion throat of the fire pot. Theburner assembly includes a fuel nozzle surrounded by an air registerthat controls the supply of air to the nozzle area from the plenumchamber, a stabilizing cone for stabilizing the flame front, and airpassage means between the stabilizing cone and the combustion throat.Either oil or gas nozzles may be employed depending upon the desires ofthe user. Further, a choke is provided in the fire pot that is flared todirect the gases being discharged from the fire pot into the desiredarea of use.

It is therefore an object of this invention to provide an improvedcombustor or burner for a steam generator, wherein the combustor iscompact and provides efficient and quite complete combustion whichapproaches stoichiometric combustion.

A further object of this invention resides in the provision of acombustor for a steam generator capable of producing high heat releaserates with comparatively low air pressures.

A still further object of this invention resides in the provision of acombustor for a steam generator having a burner assembly capable ofenabling substantially complete combustion within a combustion chamberand aiding balancing of the distribution of the resultant energy.

Another object of this invention is to provide a combustor for a steamgenerator having a burner assembly capable of inducing internalrecirculation of the combustion products within the combustion chamberand thereby to contain the fire within the combustion chamber resultingin improved combustion.

Another object of this invention is the provision of a combustor in asteam generator of simplified construction capable of inducing internalrecirculation for aiding the combustion process.

Other objects, features and advantages of the invention will be apparentfrom the following detailed disclosure, taken in conjunction with theaccompanying sheets of drawings, wherein like reference numerals referto like parts, in which:

FIG. 1 is an elevational view of a steam generator equipped with thecombustor of the present invention, showing some parts in section andother parts broken away and still other parts diagrammatically forsimplicity purposes;

FIG. 2 is a greatly enlarged side elevational view with some parts insection of a burner assembly having an oil nozzle according to thepresent invention;

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FIG. 3 is a transverse sectional view taken substantially along line 3-3of FIG. 2; and

FIG. 4 is a vertical sectional view taken through a burner assembly inaccordance with the present invention and showing a gas nozzle.

Referring now to the drawings, and particularly to FIG. 1, a steamgenerator 10 includes a combustor or burner 11 according to the presentinvention that delivers hot gases to the heat transfer means or watertubes 12. Water and steam are pumped through the water tubes 13 by meansof a circulating water pump 13, and the steam is separated from thewater in the drum 14. Since the details of the steam generator otherthan in the combustor 11 are not relavant to the present invention, theremainder of the application will refer only to the combustor 11.

The combustor 11 includes generally a fire pot 15 surrounded by a casing16 that defines therewith a plenum chamber 17, and a burner assembly 18.The plenum chamber 17 is annular and is supplied with air by means of ablower 19 so that the chamber remains pressurized during the operationof the combustor 11.

The fire pot I5 is generally cylindrical in shape and consists of arefractory lined can having a combustion throat 20 at one end and achoke 21 at the other end. The combustion throat and choke are centrallylocated in the opposite ends of the fire pot. Moreover, the choke 21 isflared at 22 for enabling the heat energy, both radiant and convective,issuing from the fire pot to be appropriately distributed into the heatexchange area of the steam generator where the water tubes 12 aremounted.

Referring now particularly to FIGS. 2 and 3, the burner assembly 18includes a mounting plate 23 secured to an opening in the casing 16 bymeans of a plurality of fasteners 24. A central opening is provided inthe plate 23 for receiving the burner nozzle unit 25. In thisillustration, an oil nozzle is shown, but it should be appreciated thata gas nozzle may be employed as shown in FIG. 4. A plurality offasteners 26 mount the burner nozzle unit 25 in place on the mountingplate 23, whereby easy removal of the burner nozzle assembly may beaccomplished for cleaning or servicing thereof. The burner nozzle unit25 includes an oil nozzle 27 and a hood 28 surrounding the nozzle forthe purpose of directing cooling air to prevent the nozzle fromvarnishing. When using gas in the burner assembly 18, it is notnecessary to employ the cooling air.

The burner assembly further includes a flange 29 mounted on a mountingplate 23, and a flange 30 in opposed spaced relation therewith forreceiving a cylindrical air register 31. The flange 30 is. suitablymounted in spaced relationship from the entrance to the combustionthroat 20 by means of spacers 32 and fasteners 33. Air passage means 34is provided between the flange 30 and the entrance to the combustionthroat 20 as seen particularly in FIG. 2.

The air register 31 defines the inte-rcommunication between the plenumchamber and the area about the nozzle 27, and includes a plurality ofcircumferentially spaced openings 35, each of which has associatedtherewith a louver or air deflector 36. Each louver 36 extends inwardlyfrom its associated opening 35 and at an angle to a radius drawn fromthe center of the air register to the point of entry within the registerof each louver. Essentially, the air register may be considered aspinner louver.

Preferably, the louvered openings are in substantial alignment with theend of the fuel nozzle 27. Also in substantial alignment with the end ofthe fuel nozzle 27 is the inlet end 37a of a stabilizing cone 37. Theoutlet -with a plurality of holes 38-.

end 37b of the stabilizing cone is adjacent to the combustion throat 20and coplanar with the end of the flange 30 adjacent to the combustionthroat. In fact, the diameter of the cone outlet 37b is substantiallyequal to the diameter of the flange 30 and is secured thereto by anysuitable means such as by welding or the like. The stabilizing cone 37is perforated and therefore provided It may be noted that the cone 37 iscoaxial with the fuel nozzle 27, the cylindrical air register 31 and theannular flange 30. Further, the air passage means or opening 34 isarranged between the outlet end of the stabilizing cone 37 and the firepot 15.

The embodiment of FIG. 4, showing a burner assembly 25a, is the same inall respects as far as operation and general construction as theembodiment of FIGS. 2 and 3 with the exception that this assembly isconstructed to employ gas as a fuel. A fuel nozzle 27a is shown havingits outer end in substantial alignment with the louvered openings andthe inlet end of the stabilizing cone. Additionally, a perforated gaspipe spreader 39 is mounted in the end of the fuel nozzle 27a forspreading the gas as it leaves the nozzle. This spreader may be of thetype shown or a cone spreader of the usual type. A pilot burner 40 isprovided to light the gases of the burner, and this pilot burner may bearranged in a suitable location such as where shown projecting throughthe mounting plate 23. It should also be understood that some pilotlighting device would be provided with the burner assembly unit 25 inthe embodiment of FIG. 2.

In operation, air is introduced into the annular plenum chamber 17surrounding the fire pot 15 in accordance with proper ratios. The air isheated as it passes over the outer surface of the fire pot 15, andthereby cools the fire pot. Then the air passes through the air-fuelmixing section of the burner assembly, wherein a predetermined amountenters the louvered openings of the air register and a predeterminedamount enters through the openings 34 under the stabilizing cone. Thespinner louvers of the air register swirl the air and provide turbulentair for thorough mixing with the fuel. Further, the spinner louvercentrifuges or spreads the mixture throughout the combustion chamber ofthe fire pot. The refractory in the fire pot reflects radiant energy tothe center of the fire pot thereby enhancing and improving combustion.Air is wiped against the stabilizing cone 37 to stabilize the flamefront, and the cone acts as a vortex sieve providing localizedrecirculation for flame stabilization and aiding of combustion.

On oil fired burner assemblies, a single air atomizing nozzle ofmulti-port design imparts the necessary atomization and momentum to thefuel for delivery into the appropriate areas for combustion. On gasfired burner units, either a cone spreader or a perforated pipe as shownis used to distribute the gas. The multi-directional streams of air andfuel meet at the combustion throat 20 where intimate mixing of air andfuel takes place. This mixture then proceeds into the combustion chamberwhere the sudden enlargement decreases the velocity to that of the fuelburning rate. As the products of combustion proceed out of thecombustion chamber of the fire pot, they are forced through the choke21, which sets up a recirculation within the combustion chamber withoutthe aid of any secondary air or apertures. This re= circulation bringsheat, ions, and radicals back into the mixing zone to aid combustion andstabilizaton. And as heretofore mentioned, radiation from the refractoryand surface combustion on the refractory also aid the burning process.As the gases issue from the choke 21, they are distributed to theirpoint of use with the aid of a flared choke surface 22. Radiant energyfrom the flare choke is also directed into the areas of use.

From the foregoing, it is appreciated that the combustor or burner ofthe present invention is capable of obtaining comparatively high heatrelease rates with low air pressure through the use of large airpassages in the air-fuel mixing section.

It will be understood that modifications and variations may be effectedwithout departing from the scope of the novel concepts of the presentinvention, but it is understood that this application is to be limitedonly by the scope of the appended claims.

The invention is hereby claimed as follows:

1. In a combustor having a fire pot with a combustion throat, a burnerassembly for the combustion throat comprising, a mounting plate spacedfrom said throat and having an opening therethrough, a burner nozzleunit mounted on said plate and projecting through said opening towardand coaxially of said combustion throat, a cylindrical air registerextending between said mounting plate and said fire pot and in coaxialalignment with said throat and said burner nozzle unit and terminatingjust short of said fire pot to define first air passage means betweentlre area about said air register and said throat, means defining secondair passage means between said area about said air register and theinterior thereof for permitting air to enter the air register behind thedischarge end of said burner nozzle unit, perforated frusto-conicalshell having its small end in substantial coaxial alignment with thedischarge end of the burner nozzle unit and its larger end terminatingat the end of the cylindrical register positioned adjacent to the firepot, and means for supplying air to said first and second air passagemeans.

2. The combination as defined in claim 1, wherein said second airpassage means includes a plurality of circumferentially spaced andradially aligned openings in said air register.

3. The combination as defined in claim 2, wherein a louver is providedfor each of said openings in the air register.

4. The combination as defined in claim 3, wherein each louver isangularly offset from a radius of said air register.

References Cited by the Examiner UNITED STATES PATENTS 1,636,616 7/1927Scheuerman l581.5 1,754,433 4/1930 Peabody 158-15 2,320,576 6/1943 Dunn158-1.5

FOREIGN PATENTS 1,252,567 12/ 1960 France.

679,145 9/1952 Great Britain.

JAMES W. WESTHAVER, Primary Examiner.

FREDERICK L. MATTESON, IR., Examiner.

E. G, FAVORS, Assistant Examiner.

1. IN A COMBUSTOR HAVING A FIRE POT WITH A COMBUSTION THROAT, A BURNERASSEMBLY FOR THE COMBUSTION THROAT COMPRISING, A MOUNTING PLATE SPACEDFROM SAID THROAT AND HAVING AN OPENING THERETHROUGH, A BURNER NOZZLEUNIT MOUNTED ON SAID PLATE AND PROJECTING THROUGH SAID OPENING TOWARDAND COAXIALLY OF SAID COMBUSTION THROAT, A CYLINDRICAL AIR REGISTEREXTENDING BETWEEN SAID MOUNTING PLATE AND SAID FIRE POT AND IN COAXIALALIGNMENT WITH SAID THROAT AND SAID BURNER NOZZLE UNIT AND TERMINATINGJUST SHORT OF SAID FIRE POT TO DEFINE FIRST AIR PASSAGE MEANS BETWEENTHE AREA ABOUT SAID AIR REGISTER AND SAID THROAT, MEANS DEFINING SECONDAIR PASSAGE MEANS BETWEEN SAID AREA ABOUT SAID AIR REGISTER AND THEINTERIOR THEREOF FOR PERMITTING AIR TO ENTER THE AIR REGISTER BEHIND THEDISCHARGE END OF SAID BURNER NOZZLE UNIT, PERFORATED FRUSTO-CONICALSHELL HAVING ITS SMALL END IN SUBSTANTIAL COXIAL ALIGNMENT WITH THEDISCHARGE END OF THE BURNER NOZZLE UNIT AND ITS LARGER